Problem with 2 dimmers

So i got 2 dimmers, i can turn them off in domoticz, no errors in the log, but when i want to turn them on i get: Connection problem (1) with Gateway : 400

Now i already re-paired the dimmers. I search google for the error, but i do not seem to be able to find a solution. Does anyone here got an idea of what i could try.
BTW i have lots of other devices, they just work. Only those 2 dimmers. It happening when i got over from one system to the other system. Reinstalled deconz, turned off deconz-gui, reinstalled domoticz plugin for deconz, But i mean, other devices just go on and off without the 400 error. So apikey must be correct. I made backup from old system and restored on new system. Anyone and idea?

Ok i just deleted the 2 dimmers and then re-paired, they seem to work again, pitty i have to edit all other stuff as they get a different idx now, but ok they work again. :-s